This invention generally relates to gas ovens, and more particularly relates to burner apparatus and method for alternately operating such burner apparatus in two different modes in a gas convection oven.
As described in U.S. Pat. No. 4,598,691, it is common for a gas oven to have two burners. One of the burners, which is commonly referred to as the bake burner, is typically a tubular ported burner that is housed in a burner box or combustion chamber located near or below the floor of the oven cavity. Hot products of combustion from the bake burner flow either directly into the oven cavity, or are used to heat a baffle which provides heat to the oven cavity. In such a manner, the oven cavity is heated to a predetermined baking temperature such as, for example 200.degree.-550.degree. F., and foods are baked therein. The bake burner may also be used in a self-clean mode of operation.
The second burner, which is commonly referred to as a broil burner, is typically located at or adjacent to the top of the oven cavity. One type of prior art broil burner is a radiant burner that has a burner head with spaced inner and outer screens covering the underside. The fuel-air mixture is introduced into the burner head and issues through the inner screen where it is ignited. In particular, the inner screen acts as a flame holder, and the flame burns on or through the outer screen thereby heating it to a predetermined luminous temperature. In turn, the outer screen gives off radiant energy that propagates downardly to broil the upper surface of food. Thus, a significant portion of the sensible heat of the flame is used to heat the outer screen which then produces a high level of radiant energy to broil food.
The above-described arrangement is relatively expensive to fabricate because two burners are used. In an attempt to provide both bake and broil modes of operation in a less expensive gas oven, a single burner has been used at the bottom of the oven cavity. The broiling is then accomplished in a separate drawer underneath the main oven cavity so that the burner is above the food. This approach, however, has a number of drawbacks. First, the normal storage space underneath the oven is lost because this region is used for the broil drawer. Also, the broil drawer is relatively low and therefore inconvenient to access. Further, a conventional tubular burner is typically used because it also provides the baking mode, and it is less effective as a broil burner.